1. Field of the Invention.
The present invention relates to a cleaning device and cleaning method, and more particularly, relates to a cleaning device and cleaning method which make possible ultra-high purity cleaning using far fewer steps than in the prior art, and without conducting heating.
2. Description of the Related Art.
Recently, the semiconductor devices formed on semiconductor substrates have become highly dense and minute, reaching the submicron level. In order to achieve a high density, it is necessary to maintain the surface of the substrate in a state of ultra-high cleanliness. That is to say, it is necessary to remove, from the surface of the substrate, organic materials, metals, various types of particles, and oxides (oxide films). It is for this reason that the surface of the substrate is cleaned.
Conventionally, a cleaning method comprising the following steps was known as a cleaning technology for attaining a substrate surface in a state of ultra-high cleanliness.
(1) 98% H.sub.2 SO.sub.4 /305 H.sub.2 O.sub.2 (at a 4:1 component ratio), temperature 130.degree. C.
In this step, the organic materials and metals are removed.
(2) Cleaning with ultra-pure water at room temperature
(3) Cleaning with dilute HF at room temperature
By means of this step, the oxide film is removed.
(4) Cleaning with ultra-pure water; room temperature
(5) 285 NH.sub.4 OH/ 30% H.sub.2 O.sub.2 /H.sub.2 O (at a component ratio of 1:1:5); temperature of 80-90.degree. C.;
By means of this step the particles are removed.
(6) Cleaning with ultra-pure water at room temperature.
(7) Cleaning with dilute HF at room temperature.
Since H.sub.2 O.sub.2 is used in step (5) above, an oxide film is formed in step (5); therefore, in this step, the oxide film is removed.
(8) Cleaning with ultra-pure water at room temperature
(9) 36% HCl/30% H.sub.2 O.sub.2 /H.sub.2 O (a component ratio of 1:1:6); temperature 80-90.degree. C. In this step, metal is removed.
(10) Cleaning with ultra-pure water at room temperature
(11) Cleaning with dilute HF at room temperature Since H.sub.2 O.sub.2 is used in step (9) above, an oxide film is formed in step (9); therefore, this oxide film is removed in this step.
(12) Cleaning with ultra-pure water at room temperature
In the conventional cleaning method described above, the following problems are present:
A) The number of steps is extremely large, i.e., 12 steps;
B) The large amount of chemicals and water issued is large;
C) High temperature steps are included; and
D) Both acidic and alkaline chemicals are employed, so that the recovery of the chemicals is difficult.
Conventionally, the vessel used for the recovery of the cleaning solution of the cleaning device is made of glass or silica. However, since glass and silica are reactive with HF, it is necessary to employ a vessel made of resin when a cleaning solution containing HF is employed.
There are also cases in which cleaning is conducted while applying vibration from the exterior of the vessel to the material to be cleaned or to the cleaning solution. When a vessel is made of glass, silica, or metal, the vibration is transmitted sufficiently to the cleaning solution or the material to be cleaned within the vessel. However, when a vessel is employed which is made of resin, the vibration is absorbed by the resin and is attenuated, and is not sufficiently transmitted to the cleaning solution or the material to be cleaned within the vessel. Since, as described above, it is necessary to employ a vessel made of resin when a cleaning solution containing HF is employed, no technology existed conventionally in which cleaning was conducted while applying vibration when a cleaning solution containing HF was employed.
The present invention has as an object thereof to provide a cleaning method having an extremely small number of steps, in which treatment can be conducted using solely room temperature steps, which uses little chemicals and water, which only employs acids, and which offers easy recovery of the chemicals employed.
The present invention also has as an object thereof to provide a cleaning device which makes it possible to conduct cleaning while applying vibration even in the case in which a cleaning solution contain HF is employed.